That would depend on the state.. It can range from a misdemeanor to a felony. I wouldn't recommend it.

Alabama: Except as otherwise provided in this Code, a person who carries concealed about his person a bowie knife or knife or instrument of like kind or description or a pistol or firearm of any other kind or an air gun shall, on conviction, be fined not less than $50.00 nor more than $500.00, and may also be imprisoned in the county jail or sentenced to hard labor for the county for not more than six months.

Virginia: A. If any person carries about his person, hidden from common observation, (i) any pistol, revolver, or other weapon designed or intended to propel a missile of any kind by action of an explosion of any combustible material; (ii) any dirk, bowie knife, switchblade knife, ballistic knife, machete, razor, slingshot, spring stick, metal knucks, or blackjack; (iii) any flailing instrument consisting of two or more rigid parts connected in such a manner as to allow them to swing freely, which may be known as a nun chahka, nun chuck, nunchaku, shuriken, or fighting chain; (iv) any disc, of whatever configuration, having at least two points or pointed blades which is designed to be thrown or propelled and which may be known as a throwing star or oriental dart; or (v) any weapon of like kind as those enumerated in this subsection, he shall be guilty of a Class 1 misdemeanor. A second violation of this section or a conviction under this section subsequent to any conviction under any substantially similar ordinance of any county, city, or town shall be punishable as a Class 6 felony, and a third or subsequent such violation shall be punishable as a Class 5 felony. For the purpose of this section, a weapon shall be deemed to be hidden from common observation when it is observable but is of such deceptive appearance as to disguise the weapon's true nature.

Washington State: 2)(a) A person shall not carry or place a loaded pistol in any vehicle unless the person has a license to carry a concealed pistol and: (i) The pistol is on the licensee's person, (ii) the licensee is within the vehicle at all times that the pistol is there, or (iii) the licensee is away from the vehicle and the pistol is locked within the vehicle and concealed from view from outside the vehicle.

(b) A violation of this subsection is a misdemeanor

Florida: 2) A person who carries a concealed firearm on or about his or her person commits a felony of the third degree, punishable as provided in s. 775.082, s. 775.083, or s. 775.084.

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"If someone has a gun and is trying to kill you, it would be reasonable to shoot back with your own gun." The Dalai Llama (5/15/01, The Seattle Times)
"That rifle on the wall of the labourer's cottage or working class flat is the symbol of democracy. It is our job to see that it stays there." George Orwell